A. Field of the Invention
This invention generally relates to methods and apparatuses related to crossbows and more specifically to methods and apparatuses related to manually assisted crossbow drawing mechanisms.
B. Description of Related Art
FIG. 1 shows a typical crossbow 10. The crossbow 10 may have a longitudinally extending main beam 12 and two outwardly extending limbs 14 which extend transversely on opposite sides of the main beam 12 from a riser 32 that may be mounted to the main beam 12. A bowstring 16 may be strung between the distal ends of the limbs 14. The main beam 12 may have a rear portion or tailstock 18 having an integrally formed butt portion 20. Butt portion 20 is normally positioned against the user's shoulder when the crossbow 10 is being aimed and fired. The main beam 12 may include an upper surface which has a longitudinally extending arrow reception groove 34 on which a projectile, such as an arrow, is positioned. The bowstring 16 may slide on this upper surface in operation of the crossbow 10. A trigger mechanism 22 of any suitable type may be supported to the main beam 12 and used to hold the bowstring 16 in a cocked condition and to release the bowstring 16. The crossbow 10 may also have a pair of pulley wheels, cams or other known devices 24 affixed to the limbs 14 to carry the bowstring 16 and one or more tension cable(s) 26 in a compound bow arrangement.
Still referring to FIG. 1, in order to operate the crossbow 10, a force must be applied to the bowstring 16 to move it from an uncocked or undrawn position, as shown in FIG. 1, to a cocked or drawn position where the bowstring 16 is held by the trigger mechanism 22. There are three general methods for applying this force to the bowstring 16. One method may be referred to as manually unassisted. For this method, no device assists the user. The user places the distal outer surface of the stirrup bracket 28 on a ground surface, places his foot into the stirrup opening 30 to thereby use his weight to hold the distal end of the stirrup bracket 28 to the ground surface, bends down to grasp the bowstring 16 with his fingers, and then pulls or draws the bowstring 16 proximally (away from the stirrup bracket 28 and toward butt portion 20) until the bowstring 16 is held or engaged by the trigger mechanism 22. While this method generally works well, it has the disadvantage of requiring the user to apply a relatively large force in order to draw the bowstring 16 to the trigger mechanism 22. Such a relatively large force makes it difficult for many users and impossible for some users to operate the crossbow. Another disadvantage of manually unassisted drawing is that generally the bowstring 16 is not drawn in an even or balanced manner so that both limbs 14 are tensioned to the same degree. Such unbalanced drawing of the bowstring 16 reduces the accuracy of the resultant shot made by the user.
With continuing reference to FIG. 1, a second method of drawing the bowstring 16 is by using an automated device (not shown). For this method, the user applies no or very little force when drawing the bowstring 16. Known automated bowstring drawing devices include motors, or other force generating devices, which may be mounted to the main beam 12. While some automated devices generally work well, they have the disadvantage of increasing the cost and the weight of the crossbow. Depending on the quality of the automated device and its installation and operation, the bowstring 16 may still be drawn in an uneven or unbalanced manner, reducing the accuracy of the resultant shot.
Still referring to FIG. 1, a third method of drawing the bowstring 16 is by using what may be referred to as a manually assisted device. For this method, a device assists the user in drawing the bowstring 16 but the user still must apply some significant, though relatively small, force. One such known device is a manual crank winch (not shown). While such winches reduce the required user force, they are often large, heavy and cumbersome. They also must be connected and disconnected from the crossbow with each use. Furthermore, they often fail to draw the bowstring 16 in an even or balanced manner. Several other manual assist devices are known but none of them provide consistent balanced performance.
With reference now to FIGS. 1-3, another example of a manually assisted device is the bowstring drawing mechanism 40. Drawing mechanism 40 may include two handles 42, 44 that support opposite ends of a string or rope 46. At least one of the handles, handle 42 in this case, may have a retracting mechanism 48 within the handle that provides a tension force on the rope 46 to “take up” or prevent unwanted “play” or “slack” in the rope 46. The retracting mechanism 48 may operate in a manner similar to the retracing mechanisms used in automobile seat belt systems. The drawing mechanism 40 may also include a bowstring engaging mechanism 50 that is used to engage or connect the rope 46 to the bowstring 16. The bowstring engaging mechanism 50 may include a pair of identical (or nearly so) engaging pieces 52, as shown. Each engaging piece 52 may have a first end 54 that receives the rope 46 and a second end 56 that receives the bowstring 16. For the example shown, the first ends 54 include a roller that is rotatable with respect to the engaging piece 52 about the longitudinal axis of a pivot pin that receives the roller. The roller has a rope contact surface that contacts the rope 46. The second ends 56 have hooks 58.
With continuing reference to FIGS. 1-3, to use the drawing mechanism 40, the user places the distal outer surface of the stirrup bracket 28 on a ground surface and places his foot into the stirrup opening 30 to thereby use his wait to hold the distal end of the stirrup bracket 28 to the ground surface. Next, the user pulls the handles 42, 44 apart and contacts the rope 46 to a proximal portion of the main beam 12 (such as to a handle or to the proximal end of the butt portion 20). As the rope 46 continues to come out of the handle(s), the user then attaches the hook 58 of one engaging piece 52 to the bowstring 16 on one side of the main beam 12 and the hook 58 of the other engaging piece 52 to the bowstring 16 on the other side of the main beam 12. The hooks 58 may be attached simultaneously. Next, the user pulls on the handles 42, 44 (one hand on each handle) proximally until the rope 46 is fully extended out of the handles 42, 44. The user continues to pull on the handles 42, 44 but now causes the bowstring 16 to move proximally until the bowstring 16 is held or engaged by the trigger mechanism 22. This arrangement provides a mechanical advantage for the user that significantly reduces the force required by the user to draw the bowstring 16 into the cocked position. The user then removes the hooks 58 from the bowstring 16, removes the drawing mechanism 40 from the crossbow 10 and stores the drawing mechanism 40 (such as by putting it in a pocket). While this method generally works well, it has the disadvantage of not always drawing the bowstring 16 in an even or balanced manner.
What is needed, is a manually assisted bowstring drawing mechanism that includes two pieces that may be selectively separated and connected together. Also needed is a manually assisted bowstring drawing mechanism that draws the bowstring in an even/balanced manner so that both limbs are tensioned to the same degree. Such devices will be easy to use and will improve the accuracy of the resultant shots made by the user.